Gas-liquid chromatography, commonly referred to as gas chromatography or GC, is a process used for analyzing a complex sample by separating the analytes within the sample to determine the identity of the analytes in the sample. Other information about the analytes, such as the concentration of each analyte within the sample, may also be obtained. A gas chromatograph is used for separating the sample by injecting the sample onto a column through which the sample passes. Different chemical analytes of the sample pass in a mobile phase at different rates depending on their various chemical and physical properties and their interaction with a specific column filling, called the stationary phase. During the process of gas chromatography, the analytes of the sample are separated as a consequence of being partitioned between the mobile gaseous phase and the stationary phase held in the column or by passing through a series of columns. The function of the mobile phase is to transport the sample through the column but not to interact with it. The sample's motion through the column is inhibited by the adsorption of the analytes either onto the column walls or onto packing materials within the column. The rate at which the analytes progress along the column depends on the strength of adsorption, which in turn depends on the properties of the analyte. Since each type of analyte has a different rate of progression, the various analytes of the sample are separated as they progress along the column and reach the end of the column at different times. A detector is used to monitor the outlet stream from the column, thus, the time at which each analyte reaches the outlet identifies the analyte and may determine the concentration of that analyte as well.
When a sample is complex and has multiple analytes it may be difficult to separate out and identify a particular analyte of interest. In multidimensional gas chromatography the sample undergoes a series of separation steps. The sample is introduced to at least two columns allowing for a better separation of the analytes. Increasing the separation of the sample increases the accuracy and the precision of the results. Multiple columns and separation steps allow for a more effective separation of the analytes from the sample, but this process does not necessarily target a particular analyte. Therefore, it would be beneficial to have a method that improves the separation of the sample and allows for the targeting of specific analytes.
The equipment used for chromatography can be expensive and, as complex samples progress through the chromatograph, build-up occurs. It would be beneficial to employ a method that keeps the equipment cleaner and reduces the need for maintenance.